Just saw a notice on Edmunds.com that Audi will be issuing a recall for the reflectors in the Xenon headlamps. Here is what Edmunds is saying:

Nature of Defect:
1. EXTERIOR LIGHTING:HEADLIGHTS Recall Number: 05V096000
Dates Manufactured: JAN 2003 to FEB 2004
Number of Vehicles Affected: 9965
Date Owners Notified On: N/A

Vehicle: 2004 Audi S4
Defect Description:
ON CERTAIN PASSENGER VEHICLES, THERE IS A POSSIBILITY OF XENON HEADLAMP COATING DEGRADATION OVER TIME. THE LUMINOUS TRANSMITTANCE OF THE HEADLAMP MAY DECREASE OVER A PERIOD OF TIME.

Consequence of Defect:
THIS CONDITION COULD AFFECT A DRIVER'S FIELD OF VIEW, INCREASING THE RISK OF A CRASH.

Corrective Action:
DEALERS WILL REPLACE THE LEFT AND RIGHT XENON HEADLAMP REFLECTORS. THE RECALL IS EXPECTED TO BEGIN DURING APRIL 2005. OWNERS SHOULD CONTACT AUDI AT 1-800-822-2834.